Well delphiniums may be a bit more delicate but I believe you could pretty much run over yarrow with a truck and it would barely notice! So go ahead and move the yarrow anytime. As long as you are careful and water well I think the delphinium should be OK although I would probably wait at least until it is finished it's bloom cycle unless there is a pressing reason to move it right away. No sense in messing up a beautiful bloom. I wouldn't wait until Spring though. Fall is a wonderful time to move perennials if you want to wait till then though.

I'm no help w/ the delphs, but it's true that you could run over yarrow w/ a truck and it would still do great. Go ahead ahd move the yarrow now if you like.

I have a lot of delphiniums and move them around all the time. As long as I keep newly transplanted delphs well watered, I don't lose any. Shelley

Every year my delphiniums grow and bloom yet they have such skinny stalks that they can’t stand upright and look constantly sad and droopy. Is that just the characteristic of the plant or can I do something to beef up the stalks/stems to make them stronger? Thank you!

Delphiniums usually need staking in my experience.